Monday, 8 February 2010

In the GSM cellular mobile phone standard, timing advance value corresponds to the length of time a signal from the mobile phone takes to reach the base station. GSM uses TDMA technology in the radio interface to share a single frequency between several users, assigning sequential timeslots to the individual users sharing a frequency. Each user transmits periodically for less than one-eighth of the time within one of the eight timeslots. Since the users are various distances from the base station and radio waves travel at the finite speed of light, the precise time at which the phone is allowed to transmit a burst of traffic within a timeslot must be adjusted accordingly. Timing Advance (TA) is the variable controlling this adjustment.

Technical Specifications 3GPP TS 05.10 and TS 45.010 describe the TA value adjustment procedures. The TA value is normally between 0 and 63, with each step representing an advance of one bit period (approximately 3.69 microseconds). With radio waves traveling at about 300,000,000 meters per second (that is 300 meters per microsecond), one TA step then represents a change in round-trip distance (twice the propagation range) of about 1,100 meters. This means that the TA value changes for each 550-meter change in the range between a mobile and the base station. This limit of 63 × 550 meters is the maximum 35 kilometers that a device can be from a base station and is the upper bound on cell placement distance.

A continually adjusted TA value avoids interference to and from other users in adjacent timeslots, thereby minimizing data loss and maintaining Mobile QoS (call quality).Timing Advance is significant for privacy and communications security, as its combination with other variables can allow GSM localization to find the device's position and tracking the mobile phone user.

The current limitation on the range of a GSM cell site to 35km is mandated by the duration of the standard timeslots defined in the GSM specification. The maximum distance is given by the maximum time that the signal from the mobile/BTS needs to reach the receiver of the mobile/BTS on time to be successfully heard. At the air interface the delay between the transmission of the downlink (BTS) and the uplink (mobile) has an offset of 3 timeslots. Until now the mobile station has used a timing advance to compensate for the propagation delay as the distance to the BTS changes. The timing advance values are coded by 6 bits, which gives the theoretical maximum BTS/mobile separation as 35km.

By implementing the Extended Range feature, the BTS is able to receive the uplink signal in two adjacent timeslots instead of one. When the mobile station reaches its maximum timing advance, i.e. maximum range, the BTS expands its hearing window with an internal timing advance that gives the necessary time for the mobile to be heard by the BTS even from the extended distance. This extra advance is the duration of a single timeslot, a 156 bit period.

Friday, 5 February 2010

A walkie-talkie, or handie talkie, (more formally known as a handheld transceiver) is a hand-held, portable, two-way radiotransceiver. Its development during the Second World War has been variously credited to Donald L. Hings, radio engineer Alfred J. Gross, and engineering teams at Motorola. Similar designs were created for other armed forces, and after the war, walkie-talkies spread to public safety and eventually commercial and jobsite work. Major characteristics include a half-duplex channel (only one radio transmits at a time, though any number can listen) and a "push-to-talk" (P.T.T) switch that starts transmission. Typical walkie-talkies resemble a telephonehandset, possibly slightly larger but still a single unit, with an antenna sticking out of the top. Where a phone's earpiece is only loud enough to be heard by the user, a walkie-talkie's built-in speaker can be heard by the user and those in the user's immediate vicinity. Hand-held transceivers may be used to communicate between each other, or to vehicle-mounted or base stations. Quoted from Wiki

Monday, 11 January 2010

SAN DIEGO AND HSINCHU – November 19, 2009 – Qualcomm Incorporated (Nasdaq: QCOM), a leading developer and innovator of advanced wireless technologies, products and services, and MediaTek, Inc., ( TPE: 2454), a leading fabless semiconductor company for wireless communications and digital multimedia solutions, today announced that they have entered into a broad patent arrangement under each company's patent portfolios, including CDMA and WCDMA essential patents, with respect to all integrated circuit products, including CDMA and WCDMA products.

MediaTek's customers do not receive rights to any of Qualcomm's patents and such customers will need to obtain a separate license from Qualcomm in order to receive rights to any of Qualcomm's patents. Qualcomm's customers do not receive rights to any of MediaTek's patents and such customers will need to obtain a separate license from MediaTek in order to receive rights to any of MediaTek's patents. The remainder of the terms of the arrangement are confidential.

MediaTek Inc. is a leading fabless semiconductor company for wireless communications and digital multimedia solutions. The company is a market leader and pioneer in cutting-edge SOC system solutions for wireless communications, high-definition TV, optical storage, DVD and Blu-ray products. Founded in 1997 and listed on Taiwan Stock Exchange under the code "2454", MediaTek is headquartered in Taiwan and has sales and research subsidiaries in Mainland China, Singapore, India, U.S., Japan, Korea, Denmark and England. For more information, please visit

Qualcomm Incorporated (Nasdaq: QCOM) is a leader in developing and delivering innovative digital wireless communications products and services based on CDMA and other advanced technologies. Headquartered in San Diego, Calif., Qualcomm is included in the S&P 100 Index, the S&P 500 Index and is a 2009 FORTUNE 500® company. For more information,

Qualcomm Forward-Looking StatementsExcept for the historical information contained herein, this news release contains forward-looking statements that are subject to risks and uncertainties, including the Company's ability to successfully design and have manufactured significant quantities of CDMA components on a timely and profitable basis, the extent and speed to which CDMA is deployed, change in economic conditions of the various markets the Company serves, as well as the other risks detailed from time to time in the Company's SEC reports, including the report on Form 10-K for the year ended September 27, 2009, and most recent Form 10-Q.